There is a continually pressing need for rapid, accurate qualitative and quantitative determinations of biologically active substances at extremely low concentrations. The purpose of the determination can be extremely varied. Today, there is a wide need for determining the presence of drugs or narcotics in body fluids, such as saliva, blood or urine. In addition, in medical diagnosis, it is frequently important to know the presence of various substances which are synthesized naturally by the body or ingested. There is also a pressing need to make such determinations by an automated method to reduce the time and effort required.